Dear Atria I took this photograph of a rainbow couple of days ago. In England you can see rainbow very often as often we have rain and sunshine in the same time. The wonderful sight of a rainbow is one of those things that bring a smile to people’s faces and something we never seem to tire of. Do you know how rainbow is created my dear Atria? Well, it is quite interesting. Rainbows happen when sunlight and rain combine in a very specific way.

You will probably know from school that the light is made up of a collection of many colours: red, orange, yellow, green, blue, indigo and violet. You can see that when you put a white light through a prism, you will see a mini-rainbow on the other side of a prism. A prism is a triangular piece of glass or plastic. The dispersion of colours in a prism occurs because of something called the refractive index of the glass. Every material has a different refractive index. When light enters a material (for example, when light traveling through the air enters the glass of a prism), the difference in the refractive index of air and glass causes the light to bend. The angle of bending is different for different wavelengths of light. As the white light moves through the two faces of the prism, the different colours bend different amounts and in doing so spread out into a rainbow.

In a rainbow, raindrops in the air act as tiny prisms. Light enters the raindrop, reflects off of the side of the drop and exits. In the process, it is broken into a spectrum just like it is in a triangular glass prism. The colour of the light that then actually makes it to your eye depends on what angle that raindrop is at, between you and the source of light, the sun.

A raindrop that is higher up in the sky will reflect red light at just the right angle for your eye. A raindrop that is a little lower in the sky will reflect green light at the right angle for your eye. Lower in the sky still and a raindrop will reflect blue light to your eye at just the right angle. Now, multiply one raindrop by millions, and high in the sky you see a band of red light, lower a band of green, and lower still and band of blue, and the other colours in between accordingly. And that is how a rainbow is formed.

If you like to experiment you can create your own rainbow in a very simple way. You will need: Water, Mirror, Scissors, Dark room, Flashlight/torch.

You need to position your glass of water on a table and then place the mirror inside it at an angle. Make sure that the room is completely dark. Close all the curtains and the blinds so it gets pitch dark. Take the flashlight or your torch and aim the light towards the mirror that you placed inside the glass. Watch a rainbow appear from the angle of your mirror. Adjust the angle of the mirror as you wish!